We acknowledge that the gender pay gap has numerous causes. But the biggest cause, as found in recent studies, is motherhood. The data shows that at age 25, college-educated women make about 90 percent as much as men. But by age 45, women make only about 55 percent as much as their male counterparts.

Thus, the gap widens for many women when they have children. The kicker: Women without children often continue to earn closer to what men do.

In law firms, that means many talented and promising female attorneys leave or reduce their work hours once they become mothers. Why? Because too many law firms continue to operate as if motherhood and parenthood impact workers' lives only in the first few months (or for fathers, the first few weeks) after the child's birth. Offering leave but failing to recognize that parents—especially mothers—may require continued support even after they return to work is a sure-fire way to lose talented lawyers to other legal employers and industries that already offer more family-supportive environments.

The obstacles law firms face in retaining new parents and fostering their success have roots not just in the traditional law firm structure, but in American society more broadly. Entrenched in our culture is the notion that working mothers are less committed to their jobs than are men with new babies, and that the mother, not father, is best suited to be the primary caretaker of young children. These beliefs are, for most people, implicit biases—beliefs we have but may not consciously confront.

One's initial reaction might be to second-guess whether these seemingly antiquated views actually still have much impact on the current American workplace. But supporting anecdotes and data abound. Consider, as just one example, the fact that the United States is the only industrialized country without a national paid family leave law (note that the Family and Medical Leave Act allows for unpaid leave only). Or consider the studies that confirm our tendency to associate men with work and women with the home. In a review of a Gender–Career Implicit Association Test, one study found that 76 percent of test takers more readily associate men with career and women with family. The test is a web-based self-assessment test designed to reveal unconscious bias by having users quickly select designated letters on a keyboard to match attributes (such as boy or girl) with one of two categories (such as science or literature).

Because subconscious associations affect the choices we make—and the policies we institute (or don't)—taking the time to evaluate this issue is more than a philosophical exercise. Without understanding what our biases are, we cannot hope to counteract them. Many legal organizations already recognize that unconscious reactions and stereotypes shape our choices and our profession. The American Bar Association has an Implicit Bias Initiative. New York's mandatory CLE requirements now include a diversity and inclusion component and California requires an hour of "Recognition and Elimination of Bias in the Legal Profession and Society." Yet law firms have room for improvement in addressing the implicit biases associated with working parents.

Importantly, this issue is not just about women. Combating motherhood bias also requires law firms to consider the narrative around male workers and fatherhood, as well. For firms that wish to make diversity, inclusion and family-friendliness more than just marketing phrases, we suggest some concrete policies:

Parental Leave Policies

The typical Am Law firm offers paid maternity leave for 12 to 16 weeks. This may have been a generous policy when it was first introduced a decade ago, but many organizations across different industries have since begun offering longer paid leave for mothers and, critically, for fathers too. According to PL+US, a paid leave advocacy organization, offering 26 weeks of paid leave to women in the United States would result in an uptick in women's labor force participation, which in turn would yield a 5 percent increase in GDP.

Beyond merely offering longer paid parental leave that reflects the needs and desires of the millennial workforce, law firms and partners should encourage both mothers and fathers to actually take the leave without fear of any associated stigma or negative impact to their careers. Indeed, equal parental leave for women and men is a concrete step law firms can take to help neutralize the prevailing biases against working mothers, and many firms and employers have begun to adopt these policies, which are also friendlier to the LGBTQ community. When men and women can and do take the same amount of leave to care for a new child, our current assumptions about women, motherhood and parenting will begin to fade, allowing a new workplace culture to take hold. This must be encouraged and supported by the attorneys the parent works with regularly in order to minimize disruptions to parental leave.

Importantly, when attorneys do take parental leave, firms must ensure that there is no detriment to compensation, promotion, class status or partnership prospects.

Flexible Work Schedules

Once parents return to work, policies that allow flexible or part-time work will allow new parents to adjust to balancing work and family. We commend those firms that have already implemented ramp-up policies, allowing attorneys to return to work after leave and to work on a part-time schedule for six months without change to their compensation, and those that permit flexible or part-time schedules permanently for their employees.

In the implementation of these flexible policies, firms should take care that these attorneys are not inadvertently punished for such reduction, thereby increasing the likelihood of attorney departures. Firms should recognize that there is a chance that a pay cut an attorney accepts to work part-time is significantly less than the attorney's actual reduction in hours. One significant matter and an attorney can often find himself or herself working 80 percent or more of a regular associate's hours for only 60 percent of the salary. Firms should, therefore, implement policies to reflect the actual hours the part-time attorney has contributed to the firm.

Child Care Policies

Managing child care hours, dropoffs, pickups, closures and sick days is a balancing act for parents. More law firms should consider partnering with child care centers in their area to provide for backup child care for their employees on days that their primary care has fallen through. Some firms have taken an additional step to provide their employees with backup in-home care, alleviating the complications associated with in-center care, such as difficulties in locating a spot in a center on short notice, ensuring the child is familiar with the environment, and ensuring care is available for a sick child.

There's also the potential for an easy, cost-effective means to lighten the load of juggling parental requirements with career demands. Law firms could easily create a "family network" within the firm to introduce parents to one another who live close to each other. The creation of the network may not only ease the burden of finding help in a pinch but increase camaraderie within the firm.

Additionally, when parents must work late, attend after-hours firm events, or travel, firms should consider subsidizing child care costs. Law firms subsidize meals and taxis home in these events; for parents, child care is an additional cost. We recognize that this policy increases the costs for law firms, but consider that firms have already spent much more recruiting talent; this extra cost to retain employees should be significantly lower than trying to recruit more talent when working parents leave the firm. Further, policies subsidizing or fully covering child care costs exist in other industries. For law firms to compete for talent, they should consider policies to alleviate the pain points of child care for employees.

Supportive Nursing Policies

Many mothers returning to work are still breastfeeding and require pumping support. Private lactation rooms are already mandated by law. Firms can engage companies such as DayOne Baby to ensure that these rooms are not only legally compliant but comfortable and effective for their employees. Firms can provide private rooms fitted for breastfeeding moms or inexpensive privacy pods. Outfitting those rooms or pods with hospital-grade pumps and other pumping supplies can help employees spend less of their work day pumping. Firms can also assist with transporting breastmilk home from business trips, whether by covering the costs of shipping (via FedEx, Milk Stork or other services) or providing travel-friendly coolers and related supplies.

Law firms and all of their attorneys and staff should also be educated about pumping and its requirements so they can be aware of the needs of new mothers. For example, a new mother may need to take breaks during depositions or long meetings to accommodate her pumping schedule. Measures should be taken to ensure that pumping moms feel free to speak up about such needs.

Some law firms have already implemented policies designed to alleviate the pain points of being a working parent, particularly a working mother. Time will tell if these policies will give these firms an advantage over others with respect to recruiting and retaining talent. But beyond these policies, if law firms are serious about inclusion, diversity and gender parity, they must not only have meaningful policies to achieve those goals, but must foster buy-in at all levels, both in theory and in practice.

The views expressed here are personal to the authors and do not represent the opinions of their employers.